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Chapter 2

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  1. Chapter 2 Chemistry!

  2. MATTER! • Everything around you is made of matter. • Matter is anything that has mass and occupies space. • What’s mass again?

  3. Composition of Matter • Elements are one of the simplest chemical substances…can’t break down! • 90 occur naturally on Earth • 25 essential to organisms • C, H, O, N… • Trace elements-present in small amounts • Iron (Fe), Magnesium (Mg), Zinc (Zn)

  4. Periodic Table • Elements are arranged in the periodic table according to physical and chemical characteristics

  5. Atoms: Building Blocks • Atoms are the smallest particles of elements that have that element’s characteristics • Review of Atomic Structure • Nucleus- • Protons- (p+) • Neutrons- (n0)

  6. Electrons and Energy Levels • Electrons form a cloud around nucleus • Travel in specific regions called energy levels. • Levels have limited capacities: • Level 1-Hold max. of 2 e- • Level 2-Hold max. of 8 e- • Level 3-Hold max. of 18 e- • Elements are stable when outer level is full

  7. Bohr Energy Level Diagrams

  8. Isotopes of Elements • Isotopes are atoms of the same element that have different numbers of neutrons. • Most Carbon contain 6 neutrons…. • Others have 7 and 8…they are isotopes of the element carbon • Referred to as C-12, C-13 and C-14 • Some are unstable-used for radiation therapy

  9. Interactions of Matter • A compound is a substance that is composed of atoms of different elements chemically combined. • Chemical reactions happen when atoms are rearranged and new bonds are formed • Compounds important to us??

  10. Bonding • Covalent Bond- two atoms sharing electrons to hold together • Hydrogen Stability • Molecules are groups of atoms held together by covalent bonds with no charge • Molecules are the simplest form of a substance that retains its properties freely

  11. Water Molecule

  12. Ionic Bonds • An atom that gains or loses electrons has an electrical charge and is called an ion. • Elements will give up/take electrons to fill outer shells • The attractive force between two opposite charged ions is an ionic bond.

  13. Ionic Bonds

  14. Section 2.2- ENERGY • Energy is defined as the ability to do work or cause change. • NRG can be in various forms and can transfer forms. • Free Energy is the NRG in a system available for work. • In cells, it’s the NRG to fuel cell processes • NRG can also change states of matter….

  15. States of Matter • Atoms in a substance are actually in constant motion. • The rate at which atoms or molecules move determines the state.

  16. Three Major States • SOLIDS: • DEFINITE VOLUME • DEFINITE SHAPE • LIQUIDS: • DEFINITE VOLUME • NO DEFINITE SHAPE (Containers’ shape) • GASES: • NO DEFINITE VOLUME • NO DEFINITE SHAPE

  17. NRG & Chemical Reactions • Metabolism is all of the chemical reactions occurring within an organism. • Reactions break down/build up molecules important to function. • Written in chemical equations using symbols and formulas.

  18. What process is this?

  19. Breakdown of RXNs • Reactants are on the left side of the equation. • Products are on the right side of the equation. • Reactant bonds are broken, atoms are rearranged, and new bonds form to make products!!

  20. Coefficients vs Subscripts • Coefficients- Big numbers before an element or compound. • Tell you how many molecules you have! • Ex.- 6CO2 means six molecules of CO2 • Subscripts- Small numbers after an element. • Tell you how many atoms you have! • Ex. – H2O means 2 atoms of H.

  21. NRG TRANSFER • Chemical reactions that involve a net release of NRG are known as exergonic. • Chemical reactions that involve a net absorption of NRG are known as endergonic. • Catalysts speed up reactions by lowering the activation NRG, or NRG needed to start the reaction.

  22. Role of Catalyst:

  23. Mixtures vs Solutions • A mixture is a combination of substances in which they retain their own properties. • Sand & Water • Solutions are mixtures in which one or more substances distribute evenly in another substance • Kool-Aid!!

  24. Solutions • Solutes are the substances dissolved in solutions. • Solvents are the substances in which the solute is dissolved. • Concentration is determined by the amount of solute dissolved in a fixed amount of solution. • If no more solute can be dissolved, the solution becomes saturated.

  25. Acids and Bases • Water molecules can be broken down into two oppositely charged ions in a process called dissociation.

  26. Acid vs Base • pH measures how acidic or alkaline (basic) a solution is. • Acid is any substance that has more hydronium ions (H3O+) in water. pH<7 • Base is any substance that has more hydroxide ions (OH-) in water. pH>7

  27. Acid/Base Characteristics • ACIDS: • Sour Taste • Can be corrosive • Examples: • BASES: • Bitter Taste • Feel slippery • Examples:

  28. Strength of Acids/Bases • Strength is based on distance from neutral, or pH of 7. • Ex. #1- A base with a pH of 13 is stronger than a base with pH of 8. • Ex. #2- An acid with a pH of 1 is stronger than an acid with a pH of 5.

  29. pH Scale • pH Scale is based on logarithmic scale. • Change in unit equals ten times the change in alkalinity or acidity. • Ex.- pH 2 is ten times stronger than pH 3.

  30. pH Scale

  31. BUFFERS!! • Living organisms are very sensitive to pH changes. • pH in organisms is controlled by buffers • Buffers can neutralize small amounts of acids or bases in a solution

  32. APE MAN!! • ATOMIC # = # Protons = # Electrons • Ex- Boron has atomic # 5 • Boron has 5 protons and 5 electrons!!

  33. MORE APE MAN!! • MASS # - ATOMIC # = # Neutrons • Ex.- Cobalt has: • Mass # = 59 • Atomic # = 27 • 59 – 27 = 32 Neutrons!

  34. Water’s Uniqueness • 1. Water is polar-it has an unequal distribution of charge. • Two Hydrogens=Positive End • Oxygen=Negative End • Molecules attract to each other and to ions • Ability to dissolve other polar substances…

  35. Hydrogen Bonding • 2. Hydrogen Bonding-the attraction of opposite charges of H and O. • Important for holding together large molecules: Proteins! • Also can occur between hydrogen and most electronegative atom in another polar molecule!

  36. Hydrogen Bonds

  37. Cohesion • 3. Cohesion is the attraction between particles of the same substance. • Creates high surface tension • Floating organisms • Beading on leaves

  38. How’d he do that?

  39. Adhesion • 4. Adhesion is the attraction between two different substances. • Allows water to creep up thin tubes: capillary action • Plants getting water from ground

  40. Specific Heat/Vaporization • 5. Water has a high specific heat. • Amount of heat NRG needed to raise/lower 1g of a substance by 1 degree Celsius. • Takes a lot to go from 0 (freezing) to 100 (boiling)! • Also has high heat of vaporization. • NRG needed to convert 1g of a liquid to gas! • Water resists temperature change. • Buffer for temperature-limits extremes

  41. Density • 6. Water expands when freezing. • Ice less dense than water!! • Lakes and Ponds…

  42. What if…..

  43. Water and Homeostasis? • What’s that word again? • How does water help?

  44. 7.3- Life Substances • Organic molecules contain carbon. • Carbon forms single, double or triple bond.

  45. Organic molecules have great variety… • Formulas for compounds may be the same but differ in structure- isomers • Also vary in size! • A polymer is a large molecule formed from bonding of smaller molecules…usually in long chains

  46. Carbohydrates • Organic compounds composed of C, H and O. • Monosaccharides-simplest type • Disaccharides-two monosaccharides • Polysaccharides-many mono. units

  47. Polysaccharides • Starch-chains of glucose used as food storage by plants • Glycogen-food storage by animals • Cellulose-cell wall and structural support for plants

  48. Lipids • Organic compounds with large proportion of C-H bonds • Commonly known as fats and oils • Insoluble in water • Composed of fatty acid chains attached to a glycerol • Used for energy storage, insulation and protection

  49. Saturated vs Unsaturated • Saturated • 1. Chains of Carbon single bonded • 2. Generally solid at room temperature • Unsaturated • 1. Chains of Carbon double bonded • 2. Generally liquid at room temperature

  50. Proteins • Large, complex polymer composed of C, H, O, N, and sometimes S. • Building Blocks=Amino Acids • 20 common AA’s • Linked by condensation-removal of -H and -OH groups to form water. Resulting covalent bond is called a peptide bond